# proto-file-parser
A Rust library and CLI tool for parsing Protocol Buffer Definition (.proto) files into JSON format.
https://crates.io/crates/proto-file-parser
## Technical Description
The parser processes .proto files through the following stages:
1. **Lexical Analysis**
- Tokenizes the input into Protocol Buffer language elements
- Handles comments, whitespace, and line continuations
- Recognizes keywords, identifiers, numbers, and special characters
2. **Syntax Parsing**
- Parses the token stream into an Abstract Syntax Tree (AST)
- Validates syntax according to Protocol Buffer Language Specification
- Handles nested message definitions and imports
3. **Semantic Analysis**
- Validates field numbers and types
- Ensures enum values are unique
- Verifies package names and imports
4. **JSON Generation**
- Converts the AST into a structured JSON format
- Preserves all relevant information from the .proto file
- Maintains nested structure relationships
## Grammar Rules
```ebnf
proto = syntax_spec package_spec? import_spec*
(message_def | enum_def | service_def)*
syntax_spec = "syntax" "=" quote ("proto2" | "proto3") quote ";"
package_spec = "package" full_ident ";"
import_spec = "import" quote import_path quote ";"
message_def = "message" ident "{" field_def* "}"
field_def = type_name ident "=" number ";"
enum_def = "enum" ident "{" enum_field* "}"
service_def = "service" ident "{" rpc_def* "}"
rpc_def = "rpc" ident "(" message_type ")"
"returns" "(" message_type ")" ";"
```
## Usage
### CLI
```bash
# Parse a .proto file and output JSON
proto-file-parser parse input.proto
# Display help information
proto-file-parser help
# Show version and credits
proto-file-parser version
```
### Library
```rust
use proto_parser::Parser;
let parser = Parser::new();
let json = parser.parse_file("input.proto")?;
println!("{}", json);
```
### Building and Testing
```bash
# Format code
make format
# Run tests
make test
# Run linter
make lint
# Run all checks before committing
make pre-commit
```